Systems and methods for locating a metal object

ABSTRACT

A device for locating an object. The device includes a housing including a first hole. The device also includes a sensor carried by the housing and comprising two or more electrodes that are positioned next to each other to form a substantially circular configuration. The sensor includes a second hole formed in the center of the circular configuration, and the second hole is axially aligned with the first hole.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/224,063, filed on Dec. 18, 2018, which is a continuation-in-part ofU.S. patent application Ser. No. 15/632,175, filed on Jun. 23, 2017,which claims priority and benefit to U.S. Provisional Application No.62/354,176, filed on Jun. 24, 2016, and titled “STUD FINDER”. The entirecontents of each of the above applications are hereby incorporatedherein by reference in their entirety.

BACKGROUND 1. Field

The present disclosure pertains to systems and methods for locating anobject, such as a stud, behind the surface of a wall structure or otherstructure.

2. Description of the Related Art

There are various existing sensing devices for sensing and locatingobjects behind walls and other building surfaces. One type of sensingdevice uses capacitive sensors for locating studs behind the surface ofthe wall or other structure. One aspect of the present applicationprovides an improvement in stud sensors, and in particular capacitivesensors for use in a stud sensing apparatus.

SUMMARY

Accordingly, one or more aspects of the present disclosure relate to astud sensor configured to locate a stud. The stud sensor comprises ahousing and a sensor carried by the housing. The sensor comprises two ormore electrodes. The two or more electrodes are configured to form asubstantially circular configuration. The stud sensor further comprisesone or more processors carried by the housing. The one or moreprocessors are communicatively coupled with the sensor. The one or moreprocessors are configured by machine-readable instructions to calculatea stud location by measuring a change in capacitance from a fixedcapacitance of a wall structure as the stud sensor is moved along asurface of the wall structure; and generate one or more signals toreport a result relating to a location of a stud.

Another aspect of the present disclosure relates to a stud sensorconfigured to locate a stud. The stud sensor comprises a housing and asensor carried by the housing. The sensor comprises two or moreinterdigitating electrodes. The stud sensor further comprises one ormore processors carried by the housing. The one or more processors arecommunicatively coupled with the sensor. The one or more processors areconfigured by machine-readable instructions to calculate a stud locationby measuring a change in capacitance from a fixed capacitance of a wallstructure as the stud sensor is moved along a surface of the wallstructure; and generate one or more signals to report a result relatingto a location of a stud.

Still another aspect of present disclosure relates to a method forlocating a stud with a stud sensor configured to locate a stud. The studsensor comprises a housing and a sensor carried by the housing. The studsensor comprises two or more electrodes configured to form asubstantially circular configuration. The stud sensor comprises audioand/or visual indicators carried by the housing, and one or moreprocessors communicatively coupled with the two or more electrodes andthe audio and/or visual indicators. The one or more processors areconfigured to generate output signal to the audio and/or visualindicators when a result relating to a location of a stud is determined.A hole is provided through the housing and substantially centeredbetween the sensors. The method comprises calculating a stud location bymeasuring a change in capacitance from a fixed capacitance of a wallstructure as a back surface of the stud sensor housing is moved along asurface of the wall structure; reporting a result relating to a locationof a stud based on the change in capacitance; indicating the resultrelating to the location of the stud via the audio and/or visualindicators; and wherein the hole is aligned with the location of thestud when the audio and/or indicators provide the indicationirrespective of the angle at which the wall engaged back surface of thehousing is oriented with respect to the wall.

These and other objects, features, and characteristics of the presentdisclosure, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts an exemplary front view of a stud sensing/stud detectingapparatus.

FIG. 1B is a schematic illustration of a stud sensing circuitry includedin the stud sensing apparatus that enables locating a stud according toone or more embodiments of the present disclosure.

FIG. 2 illustrates a shield electrode according to one or moreembodiments.

FIG. 3 illustrates two interdigitating electrodes according to one ormore embodiments.

FIG. 4 is an exemplary graph depicting signals corresponding to twoelectrodes according to one or more embodiments.

FIG. 5 is a wall depth table according to one or more embodiments.

FIG. 6 illustrates two electrodes forming a substantially circularconfiguration according to one or more embodiments.

FIG. 7 illustrates two electrodes forming a substantially circularconfiguration according to one or more embodiments.

FIG. 8 illustrates two electrodes forming a substantially circularconfiguration according to one or more embodiments.

FIG. 9 illustrates two electrodes forming a substantially circularconfiguration according to one or more embodiments.

FIG. 10 illustrates arrays of substantially square electrodes formingvarious structures according to one or more embodiments.

FIG. 11 is a wall depth table according to one or more embodiments.

FIG. 12 illustrates various examples of electrodes in substantiallytriangular patterns and other patterns according to one or moreembodiments.

FIG. 13 is a graph illustrating a progression of overlapping area of asubstantially triangular capacitive plate according to one or moreembodiments.

FIG. 14 is a graph illustrating a progression of overlapping area ofnon-rectangular capacitive plates according to one or more embodiments.

FIGS. 15-24 illustrate various views of a housing of a stud sensoraccording to one or more embodiments.

FIG. 25 illustrates an electronic hardware block diagram according toone or more embodiments.

FIG. 26 illustrates an electrode connection diagram according to one ormore embodiments.

FIG. 27 illustrates an electrode connection diagram according to one ormore embodiments.

FIG. 28 illustrates a firmware or software flowchart according to one ormore embodiments.

FIG. 29 illustrates a method for locating a stud with a stud sensoraccording to one or more embodiments.

FIG. 30 depicts an exemplary front view of a stud sensing/stud detectingapparatus.

FIG. 31 illustrates the basic concept of metal detection using aninductor.

FIG. 32 illustrates an L-C resonator, also sometimes referred to as anL-C tank.

FIG. 33A illustrates the basic components of an inductance to digitalconverter.

FIG. 33B illustrates an inductance to digital converter connected to anL-C resonator.

FIG. 34 illustrates a prior art wire and core inductor.

FIG. 35 illustrates one layer of a printed circuit board with anexemplary embodiment of an inductive coil thereon.

FIG. 36 illustrates another layer of a printed circuit board with anexemplary embodiment of an inductive coil thereon.

FIG. 37A illustrates the printed circuit board with the inductive coilsand electrodes.

FIG. 37B illustrates an exemplary embodiment of cutouts in an electrodeconfiguration.

FIG. 38 illustrates an electronic hardware block diagram.

FIG. 39 illustrates an electrode and inductive coil connection diagram.

FIG. 40 illustrates a firmware or software flowchart according to one ormore embodiments

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As used herein, the singular form of “a”, “an”, and “the” include pluralreferences unless the context clearly dictates otherwise. As usedherein, the statement that two or more parts or components are “coupled”shall mean that the parts are joined or operate together either directlyor indirectly, i.e., through one or more intermediate parts orcomponents, so long as a link occurs. As used herein, “directly coupled”means that two elements are directly in contact with each other. As usedherein, “fixedly coupled” or “fixed” means that two components arecoupled so as to move as one while maintaining a constant orientationrelative to each other.

As used herein, the word “unitary” means a component is created as asingle piece or unit. That is, a component that includes pieces that arecreated separately and then coupled together as a unit is not a“unitary” component or body. As employed herein, the statement that twoor more parts or components “engage” one another shall mean that theparts exert a force against one another either directly or through oneor more intermediate parts or components. As employed herein, the term“number” shall mean one or an integer greater than one (i.e., aplurality).

Directional phrases used herein, such as, for example and withoutlimitation, top, bottom, left, right, upper, lower, front, back, andderivatives thereof, relate to the orientation of the elements shown inthe drawings and are not limiting upon the claims unless expresslyrecited therein.

As used herein, the use of the term “stud” may refer to any hiddenobject behind the surface of a wall structure, including but not limitedto a stud, an alternating current (AC) line, etc. As used herein, theuse of the term “wall structure” or “wall” may refer to any surface suchas a wall, floor, ceiling, roof, etc. As used herein, the use of theterm “substantially circular” is not limited to a circle. Rather, thisterm refers to circles, ovals, or other rounded shapes. In addition, theterm refers to multi-sided shapes approximating a circle. For example,the term refers to octagons or other multi-sided shapes with even moresides than eight. As used herein, the use of the term “square” may referto square, substantially square, rectangular, or substantiallyrectangular. As used herein, the use of the term “diamond” may refer todiamond or substantially diamond in shape. As used herein, the use ofthe term “pyramid” may refer to pyramid or substantially pyramid inshape.

Current stud sensing devices in the market tend to utilize a singlesquare or rectangular shaped electrode (also referred to herein as astud sensor). Such stud sensing devices may work if a user moves thestud sensor in a linear and horizontal fashion along a surface of a wallstructure. However, a human's arm does not always move accurately in alinear line. Rather, a human's arm often moves in an arc like shape, orin another non-linear fashion, especially when the arm is fullystretched out. For example, if a person is reaching far up on a wallstructure to try to locate a stud to hang a painting, the person's armmay move in an arc like fashion. Oftentimes people do not maintain thestud sensors in a perfectly vertical orientation, and moreover do notmove in a linear and horizontal fashion.

Various embodiments according to the present disclosure utilizeelectrodes that form substantially circular configurations (as definedherein). The use of a substantially circular configuration for theelectrodes provisions a user to approach the stud with the stud sensorat an angle, arc or in a non-linear fashion. A stud locating indicia onthe housing will enable the user to identify the location of apredetermined location on the stud (e.g., the edge of the stud, thecenter of the stud, or both) when the sensors (cooperating with one ormore processors and audio and/or visual indicators) identify that thepredetermined location on the stud has been reached. For example, theindicia on the housing, in one embodiment, is simply a marker hole inthe housing. In another embodiment, the indicia may comprise a visualdisplay on the housing, indicating a location corresponding to a feature(e.g., edge or center) of a stud.

In the embodiment where a hole is used as the indicia, the hole issubstantially centered within the substantially circular configurationof the electrodes. In this embodiment, because the marker hole isequally spaced from all positions on the edge or perimeter of theelectrodes, the marker hole will always be located at a predeterminedlocation with respect to the stud, irrespective of the direction orangle the stud is reached from. This will be described in greater detailbelow. Just for example, in one embodiment, a substantially circularand/or interdigitating sensor configuration can have a diameter of about2.0″, or in one embodiment a diameter in the range of 1.5″ to 2.5″ andin yet another embodiment, a diameter in the range of 1.0″ to 3.0″. Adiameter of 1.5″ corresponds to the width of certain stud types (alongits edge) that would normally engage with (or be immediately behind) thedry wall. Thus, in one example for a circular sensor with a diameter of1.5″, if the hole through the housing is centered between the sensors,the center of the hole will essentially be 0.75″ from the perimeter ofthe sensor(s) in all directions. Thus, if a back surface of a housing ofthe sensing apparatus (also referred to herein as a stud finding device,or simply stud finder) is slid across the wall surface in any direction,then, when the perimeter of the substantially circular configuration ofthe sensors first reaches the edge of a stud underlying the wallsurface, the center of the hole will be positioned 0.75″ from the studedge (or substantially centered with that particular stud type). It mustbe appreciated that that this will be true regardless of whether thestud finder's housing is moved perfectly horizontally along the wallsurface (e.g., perpendicular to the stud), at a 45 degree angle or lesswith respect to the stud, or optionally at any angle of approach to thestud.

FIG. 1A depicts an exemplary front view of a stud sensing apparatus 100(also referred to herein as a stud detecting apparatus) according to oneembodiment of the present disclosure. The stud sensing apparatus 100 isconfigured to locate a stud using circuitry 10 illustrated in FIG. 1B.The stud sensing device 100 (referred to hereinafter as stud finder) isconfigured to facilitate a user to locate a stud without having to alignthe device 100 in a perfect vertical orientation, or moving the device100 in a perfect linear and horizontal fashion. In some embodiments, andas shown in FIG. 1B, the stud finder includes one or more of, aprocessor 12, electronic storage 14, and a capacitive sensor 22 (alsoreferred to herein as a stud sensor). By one embodiment, each of theprocessor 12, the capacitive sensor 22, and the electronic storage 14may be coupled to a user interface 20. The user interface 20 provisionsfor instance, functions such as tuning the parameters of the capacitivesensors and the like. Details regarding this are described later withreference to FIG. 25. In some embodiments, processor 12, electronicstorage 14, and the capacitive sensor 22 may reside in the same housing.In some embodiments, a microcontroller may be included in the samehousing within which capacitive sensor 22 resides, and may becommunicatively coupled with processor 12, electronic storage 14, andcapacitive sensor 22. In some embodiments, capacitive sensor 22 mayreside within a handheld housing.

The capacitive sensor(s) 22 may comprise two or more electrodes that mayor may not be interdigitating. Moreover, the stud finder 100 may furthercomprise one or more processors. The one or more processors may becommunicatively coupled with the capacitive sensor (22).

Processor 12 may be configured to provide information processingcapabilities in stud finder 100. As such, processor 12 may comprise oneor more of a digital processor, an analog processor, a digital circuitdesigned to process information, an analog circuit designed to processinformation, a state machine, and/or other mechanisms for electronicallyprocessing information. Although processor 12 is shown in FIG. 1B as asingle entity, this is for illustrative purposes only. In someembodiments, processor 12 may comprise a plurality of processing units.These processing units may be physically located within the same device(e.g., a server or the housing within which capacitive sensor 22resides), or processor 12 may represent processing functionality of aplurality of devices operating in coordination (e.g., a server,computing device and/or other devices.)

Furthermore, processor 12 can be configured via machine-readableinstructions 24 to execute one or more computer program components. Theone or more computer program components may comprise one or more of acalculating stud location component 26, a result reporting component 28,and/or other components. Processor 12 may be configured to executecomponents 26 and/or 28 by software; hardware; firmware; somecombination of software, hardware, and/or firmware; and/or othermechanisms for configuring processing capabilities on processor 12.

It should be appreciated that although components 26 and 28 areillustrated in FIG. 1B as being co-located within a single processingunit, in embodiments in which processor 12 comprises multiple processingunits, one or more of components 26 or 28 may be located remotely fromthe other component. The description of the functionality provided bythe different components 26 and 28 described below is for illustrativepurposes, and is not intended to be limiting, as any of components 26and 28 may provide more or less functionality than is described. Forexample, one or more of components 26 and 28 may be eliminated, and someor all of its functionality may be provided by other components. Asanother example, processor 12 may be configured to execute one or moreadditional components that may perform some or all of the functionalityattributed below to one of components 26 and/or 28.

In some embodiments, calculating stud location component 26 may beconfigured to calculate a stud location by measuring a change incapacitance from a fixed capacitance of a wall structure as the studsensor is moved along a surface of the wall structure, as known in theart. Result reporting component 28 may be configured to report a resultrelating to a location of a stud.

In one embodiment, the stud sensor 22 uses capacitive sensingelectronics to locate the center of studs and joists through a drywallor other common building materials and provides to a user an indication,either visually and/or audibly once a detection is made. The thicknessof the building materials where stud is located may be 0.5″, 0.75″, 1″and up to 1.5″ or more (or less than 0.5″), as known in the art. Usewith any other suitable thicknesses is contemplated. By one embodiment,the stud detecting device of the present disclosure may also detect AClines behind the surface of the drywall or other common buildingmaterials. Those AC lines carry the electrical power being delivered tohomes and businesses. AC voltages may be in the range of 100-240V and ACfrequencies may be in the range of 50-60 Hz. Use with lower and higherfrequencies is contemplated.

Stud sensor 22 detects a capacitive change to a sensor when a stud ispresent behind the surface of a wall structure. In some embodiments,“charge transfer in self mode” technology is the capacitance measurementtechnology used to measure a change in capacitance based upon a fixedcapacitance of the wall structure. There are several companies thatproduce “charger transfer” integrated circuit (IC) chips for userapplications including Texas Instruments' CapTIvate technology.

“Self-mode” refers to the external capacitance change relative to earthground. There are three different capacitors: a Vreg capacitor (notshown), a sampling capacitor (not shown), and an external unknowncapacitor(s) (the first and second electrodes of the capacitive sensor22, as shown in FIG. 1B) in hardware to implement the charge transfertechnology. During the charge phase, the capacitance charge stored onthe Vreg capacitor is used to charge the external unknown capacitance.Then a transfer phase begins, and the charge from the externalcapacitance is transferred to a sampling capacitor. In the meantime theVreg capacitor is recharged by a DC linear voltage regulator. Thesecharge and transfer phases are repeated until the sampling capacitor ischarged to a preset amount.

In some embodiments according to the present technology, the externalcapacitance is the electrode's capacitance change when there is stud orsimilar structure present. The hardware to implement this capacitancemeasurement is part of the peripheral of the microcontroller. Themicrocontroller's charge transfer engine settings are configured insoftware to provide high sensitivity of the system.

In one embodiment, the housing 101 (FIG. 1A) is provided with an indiciathereon to advise the user where, in relation to the housing theidentified attribute of the located stud (edge or center) is located.For example, the indicia can be a pointer on the housing, an LED displayon the housing, or simply a hole through the housing (as in theillustrated embodiment). Further details regarding the housing and theassociated components of the stud finder 100 are described later atleast, with reference to FIG. 15.

By way of a non-limiting example, FIG. 2 illustrates an optional firstshield electrode 202 (solid shield plane) according to one or moreembodiments. In one embodiment, the shield electrode 202 issubstantially circular (like the capacitive sensor electrodes), and inone embodiment the shield electrode 202 has an outer diameter that islarger than the outer diameter of the substantially circular sensorelectrodes that for the capacitive sensor 22. In another embodiment, theshield electrode 202 has an outer configuration that is notsubstantially circular. A hole 204 (or center marking channel) isprovided through the center of first shield electrode 202. In someembodiments, the hole (or center marking channel) through the center offirst shield electrode 202 may be aligned, or at least partiallyaligned, with a back hole 1514 that is disposed on a back side of thehousing (e.g., through the back half of a clam shell housing) of thestud finder (see FIG. 15). In some embodiments the hole 204 may alsoextend through the front of the housing (e.g., through a front half of aclaim shell housing). In one embodiment, the hole at the front of thehousing may be larger (or smaller) than the hole at the back of thehousing. In one embodiment, the hole 204 extends through the housing andthrough the shield electrode (as well as the substantially circularand/or interdigitating electrodes forming the capacitive sensor as willbe described). As such, the hole is substantially centered with respectto the periphery of these electrodes. The hole is configured to bealigned with an edge of a stud, or in some embodiments with the centerof a stud, when an audio and/or visual indicator reports a resultrelated to a location of a stud. For example, the audio indicator cantake the form of a speaker, vibrator, or other noise maker that emits asound when the edge (and/or center) of a stud is reached or located. Inaddition, or alternatively, a visual indicator such as an LED, LCD, orother visual indicator can provide a visual indication, when the edge(and/or center) of a stud is reach or located. A pencil or pen may beinserted through hole 204 to mark the wall surface at a location of thewall behind which a stud has been detected. In another embodiment (notillustrated), rather than a hole (and instead of the user using a pen orpencil to mark the wall surface), the central region of the housing(where the hole 204 is located) can instead be provided with a springbiased button. The button has a finger engaging surface at the frontside of the housing, and an extendable pin or pointed projection that isnormally withdrawn inside the housing and can be forced rearwardlybeyond the back surface of the housing, against the spring bias of thebutton when the button is depressed by a user, to engage the wallsurface to create a small hole or mark on the wall surface. The smallhole or mark created by the pin or pointed projection will correspond tothe center of the stud, when a stud has been detected.

By one aspect of the present disclosure, the first shield electrode 202is disposed on a back side (placed in apposition or substantially inapposition with a wall structure) of a printed circuit board (PCB) 206.Moreover, the first shield electrode 202 is driven at a same potentialas the two interdigitating electrodes 302 and 304 of FIG. 3. The utilityof the shield electrode as well as its relative positioning with respectto the PCB and the interdigitating electrodes is described next withreference to FIG. 3.

In the embodiment where a hole 204 is used as the indicia, the hole issubstantially centered within the substantially circular configurationof the electrodes. This can be appreciated from the configurations shownin FIGS. 6-9. In these embodiments, because the marker hole 204 isequally spaced from all positions on the edge or perimeter of theelectrodes, the marker hole will always be located at a predeterminedlocation with respect to the stud, irrespective of the direction orangle the stud is reached from. For instance, the stud finder need notbe held perfectly in a vertical fashion in order to detect the stud.Even if the stud finder is disposed at an angle with respect to thewall, the stud finder of the present disclosure enables accuratedetection of the stud due to the configuration of the capacitive sensorsdescribed herein. Just for example, in one embodiment, a substantiallycircular sensor configuration can have a diameter of 1.5″ (whichcorresponds to the width of certain stud types along its edge that wouldnormally engage (or be immediately behind) the dry wall. If the hole 204though the housing and centered between the sensors is centered, thecenter of the hole will essentially be approximately 0.75″ from theperimeter of the sensors in all directions. Thus, if the stud sensorhousing back surface is slid across the wall surface in any direction,when the perimeter of the substantially circular configuration of thesensors first reaches the edge of a stud underlying the wall surface,the center of the hole will be positioned 0.75″ from the stud edge (orsubstantially centered with that particular stud type). This will betrue whether the stud finder housing is moved perfectly horizontallyalong the wall surface (e.g., perpendicular to the stud), at a 45 degreeangle or less with respect to the stud, or optionally any angle ofapproach to the stud.

FIG. 3 illustrates two interdigitating electrodes according to one ormore embodiments. The term “interdigitating” as used herein is definedto mean folded or locked together. This may mean, for example, that oneelectrode may not be moved relative to another electrode on at least oneaxis. The two interdigitating electrodes include first electrode 302 andsecond electrode 304. In some embodiments, the electrodes may not beinterdigitating. In one embodiment, there is a gap 306 formed betweenfirst electrode 302 and second electrode 304, and an outer perimeter312. In some embodiments, gap 306 may be approximately 0.2 mm, however,any other suitable values are contemplated. For instance, the gap 306may be in the range from 0.05 mm to 0.3 mm, and in another embodiment,in the range 0.15 mm to 0.25 mm Note that the gap 306 providesinsulation between the first electrode 302 and the second electrode 306.

By one embodiment of the present disclosure, it is envisioned that asecond shield electrode 308, that is substantially ring-shaped, may beincluded in the stud sensor. Accordingly, the first electrode 302,second electrode 304, first shield electrode 202, and second shiedelectrode 308 form a capacitive sensor. The sensor design choiceprovides sufficient sensitivity and minimizes noise from parasiticcapacitance. By one embodiment, the interdigitating electrodes aredisposed on a top layer of PCB 206, and surrounded at its periphery bysecond shield electrode 308. The first shield electrode 202 can bedisposed by one embodiment, across the bottom layer of the PCB. Thefirst shield electrode 202 and second shield electrode 308 areelectrically coupled and/or communicatively coupled with respect to eachother and with respect to first electrode 302 and second electrode 304.There is a gap 310 between the electrodes (first electrode 302 andsecond electrode 304) and second shield electrode 308. In someembodiments, gap 310 may be approximately 0.8 mm, however, any othersuitable values are contemplated. For instance, the gap 310 may be inthe range 0.5 mm to 0.8 mm, and in one embodiment, in the range of 0.6mm to 0.7 mm. The combination of charge transfer in self mode technologywith an interdigitating electrode sensor enables accurate detection ofstud centers on thicker walls over other stud finders on the market. Anaccelerometer, humidity detector, and temperature detector may provideincreased reliability.

The shield electrodes disclosed herein are optional, and can be omittedfrom the embodiments described. When they are provided, they providevarious functionality to the stud finder. For example, in someembodiments they can reduce noise because they are the ground plane ofthe PCB. Secondly, the shield electrodes are driven at the samepotential as first electrode 302 and second electrode 304. This drivenshield minimizes the parasitic capacitance and increases the sensor'ssensitivity.

In some embodiments, the combination of first electrode 302 and secondelectrode 304 generate a total of two signals that indicate a change incapacitance when there is stud behind the surface of the wall structureand the stud is in proximity with the capacitive sensor. The signalvalue will drop gradually when the electrodes 302 and 304 (i.e.,together the capacitive sensor) passes over the stud and graduallyincrease after the capacitive sensor passes the stud as shown in FIG. 4.The software and/or firmware in a microcontroller can be configured tocontinuously monitor the signal values. The changes in value isrecognized by software and/or firmware and used to determine thepresence and/or location of a stud.

By way of a non-limiting example, FIG. 4 illustrates two electrodes'signal graph 400 according to one or more embodiments. The horizontalaxis 402 represents the number of samples of capacitance taken ascapacitive sensor 22 travels across a surface of a wall structure (fromleft to right in this case). The vertical axis 404 does not have units,but represents a relative change in capacitance as capacitive sensor 22travel across the surface. Waveform 406 represents a signal reading fromfirst electrode 302. Waveform 408 represents a signal reading fromsecond electrode 304. The signals are at their lowest points at studcenter line 410. When the waveforms reach this low point, capacitivesensor 22 is centered over the stud. For instance, referring to FIG. 1B,when sweeping capacitive sensor 22 from left to right, for example, theelectrode to the sensor's right (i.e., the electrode labeled as the2^(nd) electrode) would be activated when encountering a stud.Subsequently, the electrode to the sensor's left (i.e., the electrodelabeled as the 1^(st) electrode) would be activated as the electrode tothe sensor's right is being deactivated.

The number and area of the electrodes are selected to provide sufficientsignal strength to detect a stud through the maximum specified thicknessof wall based on the capacitance equation:

C=E×A/d   Equation 1

where E is the dielectric constant, A is the area of contact of sensor22 (i.e., the circular area of the capacitive sensor 22) with a wallstructure, and d is the distance between the capacitive sensor and thestud (or the wall thickness in some embodiments).

In some embodiments, the sensor is designed in substantially circularshape for symmetry. One aspect of the substantially circular shape, asexplained above, is that the signals (see FIG. 4) are tolerant of theangle of the movement of capacitive sensor 22. One embodiment, thecapacitive sensor 22 will work best when the user approaches a stud atan angle of less than 45° (movement by the user). This is because atgreater angles, the two electrodes may approach the stud at the sametime (e.g., if the stud sensor approached the stud at 90°, with the toppart of the housing moving into/toward the stud). Of course, this anglecan be engineered and designed as desired.

FIG. 5 is a wall depth table according to one or more embodiments. Incapacitance equation 1 above, the area of the combination of twoelectrodes is in direct relationship to capacitance. This table defines,in some embodiments, the minimum round area of two electrodes withrespect to wall depth that will generate good and reliable detectioncapacitance change results. The numbers in this wall depth table aremerely exemplary in nature and not intended to be limiting. Other valuesare envisioned.

FIG. 6 illustrates two interdigitating electrodes forming asubstantially circular configuration according to one or moreembodiments. A first electrode 602 and a second electrode 604 separatedby an interface 606. A hole 204 (or 1514, see FIG. 15) is providedthrough the electrodes (or at the interface between the electrodes) asillustrated and discussed herein. A yin-yang or s-shaped pattern may beformed in the embodiment of FIG. 6. First electrode 602 and secondelectrode 604 may meet at a variety of different curves and/or linesegment(s). The substantially circular configuration formed by the twoelectrodes of FIGS. 6-9 may have a diameter ranging betweenapproximately 1″ to 3″. However, other values are contemplated.Moreover, in one embodiment, the diameter of the shield electrode 202 isgreater than the diameter of the circular configuration formed by thefirst electrode 602 and the second electrode 604. For instance, thediameter of the shield in one embodiment is in the range 1.5″ to 3.5″.In another embodiment, the shield electrode has a diameter than issmaller than the first electrode

FIG. 7 illustrates two electrodes forming a substantially circularconfiguration according to one or more embodiments. A first electrode702, and a second electrode 704 meet at a gap 706 and a hole 204 asdiscussed herein. First electrode 702 and second electrode 704 are eachin the shape of a semi-circle, or a substantially semi-circular shape.Interface 706 is in the form of a line segment with hole 204 therethrough. The configuration of the electrode illustrated in FIG. 7 is notinterdigitating.

FIG. 8 illustrates two interdigitating electrodes forming asubstantially circular configuration according to one or moreembodiments. A first electrode 802 and a second electrode 804 meet atinterface or gap 806 and comprises a hole 204 there through as discussedherein. A saw-tooth or zig-zag pattern is formed by the interface forthe embodiment of FIG. 8. Interface 806 has three line segments with thecentral line segments having hole 204 there through.

FIG. 9 illustrates two interdigitating electrodes forming asubstantially circular configuration according to one or moreembodiments. A first electrode 902 and a second electrode 904 meet atinterface or gap 906 and comprises hole 204 as discussed herein. As canbe seen in FIG. 9, the interface between first electrode 902 and asecond electrode 904 comprises a plurality of curved lines. All othersuitable patterns are contemplated but are not shown herein for the sakeof brevity.

Interdigitating electrodes provide higher sensitivity thannon-interdigitating electrodes. If there are N number of electrodes, theratio of each electrode's area to the whole area of the substantiallycircular capacitive place is 1:N in some embodiments. In one embodiment,the shape of a given electrode is the mirror image of the otherelectrode within the circular area; those electrodes are interlocking(interdigitating) in some embodiments. However, it must be appreciatedthat the N electrodes that are interdigitated form a substantiallycircular configuration.

FIG. 10 illustrates arrays of substantially square two-dimensionalelectrodes forming various structures according to one or moreembodiments. The diamond pattern comprises multiple square electrodesarranged in an N×N array and formed in substantially diamond shape. Thepyramid pattern comprises multiple square electrodes arranged in N×Marray and formed in a substantially pyramid shape. The configuration ofelectrodes enables capacitive sensor 22 to be omnidirectional. Studsensor 22 may be moved at any angle and still detect a predetermined ordesired location of stud (e.g., the edge or center) irrespective of theangle at which the wall engaged back surface of the housing ofcapacitive sensor 22 is oriented with respect to the wall.

Additionally, based on the location of the electrodes and changes inelectric potential of the electrodes, stud sensing device 100 mayindicate the orientation of a stud. These attributes may also apply toother embodiments, such as the embodiments of FIGS. 6-9. For example, asdescribed in the U.S. Provisional Application No. 62/354,176, (and withreference therein to FIGS. 5 and 6A), the electrodes overlapping thestud area constantly changes due to the shape of the electrodes as thestud finder is moved across the wall. Accordingly, as the capacitance ofcertain electrodes (within the pyramid or diamond style configuration ofFIG. 10) changes, the stud finder may be configured to estimate theorientation of the stud.

By one embodiment, the substantially circular configuration ofelectrodes enables capacitive sensor 22 to be omnidirectional. Incontrast, as a rectangular electrode crosses over a stud, the overlaparea with respect to the electrode and the stud will not increase at apredictable rate if the rectangular electrode is not aligned vertically.For example, a corner of the electrode may first overlap a stud if theelectrode is not aligned vertically with respect to a wall structure.Providing a substantially circular configuration overcomes this problemand allows for the sensor to not be aligned vertically and to be movedin a non-linear fashion.

FIG. 11 is a wall depth table according to one or more embodiments. Thistable defines, in some embodiments, the minimum square electrode area ofa square electrode with respect to wall depth that will generate cleanand reliable detection capacitance change results. The numbers in thiswall depth table are merely exemplary in nature and not intended to belimiting. Other values are envisioned.

FIG. 12 illustrates various examples of electrodes in substantiallytriangular patterns and other patterns according to one or moreembodiments. These patterns were discussed in U.S. ProvisionalApplication No. 62/354,176, filed on Jun. 24, 2016 and titled “STUDFINDER,” the content of which is incorporated herein in its entirety byreference. The patterns comprise one or multiple modified forms ofsubstantially triangular or substantially rectangular electrodes. Duringoperation, the part of the electrode overlapping the stud area ischanging due to the shape of electrode. The changing area generates adirect proportional capacitance change. Moreover, the relationshipbetween the shape and overlapping area is explained in FIGS. 6A and 6Bof the '176 provisional patent application.

FIG. 13 is a graph illustrating a progression of overlapping area of asubstantially triangular capacitive plate according to one or moreembodiments. FIG. 13 corresponds to FIG. 6A of the '176 provisionalpatent application and was described therein.

FIG. 14 is a graph illustrating a progression of overlapping area ofnon-rectangular capacitive plates according to one or more embodiments.FIG. 14 corresponds to FIG. 6B of the '176 provisional patentapplication and was described therein.

FIGS. 15-24 illustrate various views of designs of a housing ofcapacitive sensor 22 according to one or more embodiments. In some ofthe figures, back hole 1514 is depicted as smaller than hole 204.However, in some embodiments back hole 1514 is larger than hole 204 andmay be located at the front of housing 1500 with hole 204 being smallerand located at the back of housing 1500. FIGS. 15-19 differaesthetically with respect to FIGS. 20-24, as can be seen in thefigures. In some embodiments, the sensor and electronic control circuitsare laid out in one PCB and the top side of PCB is enclosed in a plastichousing 1500. The housing is designed to be user-friendly and ergonomic.The back of the PCB is covered in an overlay material made ofadhesive-backed film with a thickness of approximately 0.005″. However,other values are envisioned. The overlay material may or may not includelabeling. This material is better than the felt pads used on the mostcurrent stud finders in the market because it provides very smoothmovement and reduces the assembly parts. Furthermore, the use of theoverlay material also eliminates an air gap that is created by usingmultiple smaller pads, thus increasing dielectric coupling. Because theproduct slides smoothly on the wall, it can start and stop quickly sothe user gets an accurate location of a stud center.

In some embodiments, housing 1500 includes power button 1502, batterycompartment 1504, LEDs 1506, 1508, and 1510, AC detector LED 1512, hole204, and back hole 1514. In some embodiments, hole 204 may have adiameter greater than that of back hole 1514; however, this need not bethe case. In some embodiments, hole 204 may have a diameter less thanthat of back hole 1514. In some embodiments, hole 204 may have adiameter equal to that of back hole 1514. In some embodiments, hole 204may be the hole through the center of the capacitive plate formed fromfirst electrode 302 and second electrode 304 and may be located at theback of housing 1500. The back of housing 1500 is the face of thehousing that is put in apposition with a surface of a wall structure.Hole 204 may go through first electrode 302, second electrode 304, andform an opening in the back of housing 1500 that may lead to a surfaceof a wall structure. In some embodiments, hole 1514 may be the holethrough the center of the capacitive plate formed from first electrode302 and second electrode 304. In some embodiments, hole 204 may be theback hole and what was referred to as back hole 1514 may be the hole inthe front of housing 1500. The front of housing 1500 is the part ofhousing 1500 that is opposite to the back of housing 1500. The front ofhousing 1500 is not put in apposition with a surface of a wallstructure. The user may view the front of housing 1500 while sweepingthe back of housing 1500 across a surface of a wall structure. The frontof housing 1500 may include elements such as LEDs and a power button insome embodiments. Battery compartment 1504 may be configuredhorizontally (as in FIG. 15) or vertically (as in FIG. 20). A hole(1514) formed through the housing 1500 may be centered or substantiallycentered with respect to the hole (204) formed between the capacitiveplates (i.e., the first electrode 302 and second electrode 304).

Another feature of housing 1500 is the power button's location anddesign, which assists the user in holding the housing 1500 evenly on awall structure, thereby generating a clean signal. Yet another featurestanding out from the current stud finder products is the thin profileof the body which can be easily put into user's pocket.

As mentioned previously, an opening (hole 204) in the center of sensor22, and correspondingly the opening 1514 on the housing of the studfinder are intended for the user to draw a mark on the wall through theopening when the stud is detected. In doing so, encourages the user tomark the center of the detecting electrodes instead of the traditionallinear offset marking channel, eliminating some potential for error.

In some embodiments, when the housing 1500 is swept across the surfaceof a wall structure, LED 1506 lights up (i.e., activated), when a studis proximate to capacitive sensor 22 and to the left of the center ofthe sensor (the electrodes) of capacitive sensor 22. When sweeping thehousing 1500 across the surface of a wall structure, LED 1510 lights upwhen a stud is located approximately at the center of the sensor ofcapacitive sensor 22 and to the right of the center of the sensor ofcapacitive sensor 22. At that point, the user can use a pencil or pen tomark the wall surface through the hole 204, which should be aligned withthe center of the stud at that point. When sweeping housing 1500 acrossthe surface of a wall structure, LED 1508 lights up when a stud isapproximately at the center of the sensor of capacitive sensor 22.Again, at that point, the user can use a pencil or pen to mark the wallsurface through the hole 204, which should be aligned with the center ofthe stud at that point. Other forms of reporting the location of a stud(or more specifically, a position on the stud such as the edge orcenter) are contemplated, such as audio signals, digital readouts,vibration, etc. AC detector LED 1512 lights up when an AC line islocated. Audio or graphical display may also be used to indicate thedetection of an AC line. Other forms of reporting the location of an ACline are contemplated.

FIG. 16 illustrates a back view of housing 1500, whereas FIG. 17 depictsan isometric view of the stud finder 100. Moreover, FIGS. 18 and 19depict a side view, and a trimetric view of the stud finder,respectively. Referring to FIG. 16, tab 1600 may be actuated to openbattery cover 1602 of battery compartment 1504 (as shown in FIG. 17). Insome embodiments, the back hole may be hole 204. In some embodiments,the back hole may be back hole 1514 and may be smaller than hole 204.This holds true for all the figures in some embodiments.

FIG. 20 illustrates a front view of another design of housing 1500. Insome embodiments, housing 1500 additionally includes a power on LED2000, a power button 2002, and a cover 2004 to a battery compartmentthat is configured vertically instead of horizontally.

FIG. 21 illustrates a back view of the design of housing 1500 of FIG.20. Hole 1514 and cover 2004 to the battery compartment are shown. FIGS.22 and 23 depict isometric and trimetric views of the stud finder ofFIG. 20, whereas FIG. 24 illustrates a side view of the design ofhousing 1500 of FIG. 20.

FIG. 25 illustrates an electronic hardware block diagram 2500 accordingto one or more embodiments. In some embodiments, electronic hardwareblock diagram 2500 may comprise a microcontroller 2502, a chargetransfer engine 2504, electrodes 2506 (the sensor of capacitive sensor22), an AC detection module 2508, a battery/voltage regulator 2510, abuzzer/LEDs (that may be part of user interface 2514), a programmingconnector 2516, a serial communication block 2518, and/or otherelements. Microcontroller's 2502 integrated charge transfer engine 2504may use charge transfer technology to measure the capacitance change inelectrodes 2506 (the sensor of capacitive sensor 22) because eachelectrode is a self-capacitive sensor in some embodiments. In someembodiments, each electrode including the shield node is mapped to thecharge transfer engine's 2504 port pin as shown in FIGS. 26 and 27. Thecontrol of the charge and transfer phases and the conversion rate areconfigured in charge transfer engine 2504 and controlled by chargetransfer engine 2504. Microcontroller 2502 scans the electrodes inparallel. This capability reduces the scan time and power consumption.In some embodiments, charge transfer engine 2504 may be integrated inmicrocontroller 2502. In some embodiments, charge transfer engine 2504may be outside of microcontroller 2502.

In some embodiments, as indicated, a buzzer and visual indicators suchas LEDs (or other indicators) may be part of user interface 2514. Abuzzer may sound and a colored visual indicator such as red light on thehousing may light up when the center of a stud is detected. Othercolored visual indicators such as, for example, a yellow light may lightup when approaching or leaving the stud area. When an AC line isdetected, a buzzer may sound and a colored visual indicator such as redlight on the product may light up to indicate there is AC line within aspecified distance from the device. Programming connector 2516 connectedto microcontroller 2502 may enable a program on the PCB to be updatedusing a computer. Serial communication block 2518 may enablemicrocontroller 2502 to send and receive the data through a serial porton microcontroller 2502.

By one embodiment, because of the fast electrode scanning time and lowpower consumption, capacitive sensor 22 is able to be powered by lowpower sources such as, for example, 2 AAA batteries. The small size ofthe batteries allows housing 1500 to be small and portable. In someembodiments, the hardware design may use surface-mount components. Thisreduces assembly time and cost. Because, in some embodiments, there areno through-hole components on the back side of the PCB, the overlaymaterial may be directly applied over the back of the PCB without theneed for another smooth plate. This further reduces assembly time andcost, and also allows housing 1500 to be small and portable.

Firmware of the stud finder may run on microcontroller 2502. Thefirmware may comprise, in some embodiments, three main softwaresegments: charge transfer engine configuration code, stud sensorapplication code, and data communication code.

The charge transfer engine configuration code sets the capacitance modeto SELF mode; assigns all the sensor elements to the appropriate portpins on microcontroller 2504; and optimizes sensor 22 tuning parameterssuch as conversion gain, conversion count, and scan time to create highsensitivity for stud detection. It scans the sensors in parallel, whichreduces operating time and saves battery power. It also automaticallycalibrates the sensor data so the system does not require a user to waitfor a few seconds for calibration after powering up.

In some embodiments, the stud sensor application code is designed withan algorithm to detect a stud behind the surface of walls of 0.5″ and0.75″ thickness. However, other values (e.g., 1″ and 1.5″) are alsocontemplated. During various running cycles, firmware reads in the rawcapacitance data from capacitive sensor 22, smooths out the noise in thedata, and checks the current data against the previous data to look forthe data trend direction. In FIG. 4, it is shown that the stud center islocated when the waveforms reach their lowest points. Data moves in adownward trend when approaching a stud and an upward trend when leavinga stud. As soon as the data changes from a downward trend to an upwardtrend, the firmware will alert the user with a colored visual indicator(or other indicator) such as red light and buzzer sound to indicate astud is detected. The firmware sets a threshold of the capacitance datavalue change for different wall thicknesses. If the capacitance datavalue change does not reach the threshold, it will not be recognized bythe software as a valid stud in order to prevent misdetection. Thisthreshold value is also used to predict a wall's thickness.

AC detection circuits send a signal to microcontroller 2502 when an ACline is detected within a given distance range. The firmware (orsoftware) will alert the user with a colored visual indicator (or otherindicator) such as red light and buzzer sound to indicate the AC linehas been detected.

FIG. 28 illustrates a firmware or software flowchart 2800 according toone or more embodiments. At an operation 2802, the stud finder can beinitialized. This may include adjusting various setting, and performinga setup operation including configuring communication ports andmicrocontroller 2502.

At an operation 2804, the sensor (two electrodes that may beinterdigitating, and the shield electrode) of capacitive sensor 22 areinitialized. This may include setting up a configuration for theelectrodes and changing various settings, parameters, etc. For instance,by one embodiment, the previously described functions performed by thecharge transfer engine are performed in this step.

At an operation 2806, stud data may be initialized by setting at leastone capacitance variable to a specified value.

At an operation 2808, a system refresh is performed so the stud data isread from the two or more electrodes, the data being related to acapacitance behind a surface. This capacitance variable will change ascapacitive sensor 22 approaches a stud and a measured capacitancechanges. The capacitance variable represents the measured capacitance ata location behind a surface of a wall structure. More specifically, oneor more processors modify the capacitance variable as a measuredcapacitance of the wall structure at a position of the sensor withrespect to the wall structure changes, the capacitance variable beingdirectly proportional to the measured capacitance of the wall structureat the position of the sensor.

At an operation 2810, a stud location is calculated by determining whenthe waveforms of FIG. 4 reach their lowest point. That is, when thecapacitance and capacitance variable(s) reach their lowest value(s). Insome embodiments, detecting the location of a stud may include detectingan edge of a stud, a center of a stud, or both. In some embodiments, apicture of an entire stud may be shown. In other words, an array of LEDsmay be implemented and only the LEDs that are determined to be above thestud may be illuminated. In this way, a user may see where the middleand/or ends of the stud are located. Alternatively, a single LED may beutilized to indicate when the center of the stud is detected.

At an operation 2812, when a stud has been located a result is reportedto the user. This may be done if a variety of ways. For example, LEDs, agraphical display, audio, etc. may be used to indicate proximity of astud or an exact or substantially exact location of a stud. The processthen proceeds to operation 2808. The refresh may be automatic in someembodiments. The refresh may be initiated manually in some embodiments.

At an operation 2812, AC line detection is performed as is known in theart.

At an operation 2816, AC detector LED 1512 lights up if an AC line isdetected. Audio or a graphical display may also be used to indicate thedetection of an AC line. The process then proceeds to operation 2812. Ifno AC line is detected, then the process proceeds to operation 2808. Therefresh may be automatic in some embodiments. The refresh may beinitiated manually in some embodiments.

FIG. 29 illustrates a method 2900 for locating a stud with capacitivesensor 22 configured to locate a stud according to one or moreembodiments. Stud sensor 22 comprises housing 1500 and a sensor carriedby housing 1500. The sensor comprises two or more electrodes. Studsensor 22 further comprises one or more processors communicativelyand/or electrically coupled with the two or more electrodes. In someembodiments, the two or more electrodes may be interdigitating. The oneor more processors are configured by machine-readable instructions toexecute computer program components. The computer program componentscomprise calculating stud location component 26, result reportingcomponent 28, and/or other components.

The operations of method 2900 presented below are intended to beillustrative. In some embodiments, method 2900 may be accomplished withone or more additional operations not described, and/or without one ormore of the operations discussed. Additionally, the order in which theoperations of method 2900 are illustrated in FIG. 29 and described belowis not intended to be limiting.

In some embodiments, method 2900 may be implemented in one or moreprocessing devices (e.g., a digital processor, an analog processor, adigital circuit designed to process information, an analog circuitdesigned to process information, a state machine, and/or othermechanisms for electronically processing information). The one or moreprocessing devices may include one or more devices executing some or allof the operations of method 2900 in response to instructions storedelectronically on an electronic storage medium. The one or moreprocessing devices may include one or more devices configured throughhardware, firmware, and/or software to be specifically designed forexecution of one or more of the operations of method 2900.

At an operation 2902, the location of a stud is calculated. In someembodiments, operation 2902 is performed by a processor component thesame as or similar to calculating stud location component 26 (shown inFIG. 1B and described herein).

At an operation 2904, results related to a stud location are reported.In some embodiments, operation 2904 is performed by a processorcomponent the same as or similar to result reporting component 28 (shownin FIG. 1B and described herein).

In another exemplary embodiment, the stud finder may include a metaldetector, as shown by the embodiment of FIG. 30 which illustrates studfinder 101. Stud finder 101 may include all of the features,embodiments, and options of stud finder 100. Additionally, the studfinder 101 includes a metal detection feature. As shown in FIG. 30, thestud finder 101 includes a metal detection indicator 3000 on its housing1500. The metal detection indicator 3000 indicates when a metal objecthas been detected. Typically the metal object being detected is behind awork surface, wall or other object such that it is not visible. Themetal detection indicator 3000 may be an LED which is activated when ametal object is detected. In other embodiments, the metal detectionindicator may be more than one LED or the indicator may be comprised ofother elements such a light, LCD screen, sound, other display or otherindication. In some embodiments, the metal detection indicator may varydepending upon the strength of the metal detection. For example, theremay be three LED indicators and an increasing number of LED indicatorsmay be activated as the strength of the detection increases (i.e., oneLED is activated when the signal is weak and three LEDs are activatedwhen the signal is strong.).

A metal object can be sensed by an inductor. FIG. 31 illustrates thebasic concept of metal detection with an inductor. As shown in FIG. 31,there is a conductive metal 3010. There is also an inductor 3011 with anAC current running through the inductor 3011. When the inductor 3011gets close to the conductive metal 3010, an eddy current is induced inthe metal 3010.

FIG. 32 illustrates an L-C resonator, or L-C tank 3020. The L-Cresonator includes an inductor and a capacitor, and generates anelectromagnetic field. As a metal object, such as the conductive metal3010, gets close to the L-C resonator, the magnetic field of the L-Cresonator is disrupted. This disruption can be detected.

FIG. 33A illustrates the basic components of the inductance to digitalconverter 3030. The inductance to digital converter 3030 includes aresonant circuit driver 3031 and a core circuit 3032. The core circuit3032 measures and digitizes the sensor frequency and outputs a digitalvalue (digital output). The inductance to digital converter 3030 can beused in a metal detection sensor.

For example, FIG. 33B illustrates an inductance to digital converter3030 connected to an L-C resonator 3020. The inductance to digitalconverter 3030 measures and digitizes the signal from the L-C resonator3020 as it moves near the conductive metal 3010 and outputs a digitalsignal. The digital signal can be processed by a microcontroller, andthe microcontroller and provide an indication of whether the stud finder101 is near a metal object 3010. The indication may be activation ofindicator 3000, as discussed above.

In prior art stud finders, a wire 3040 was wound about a core 3041 tocreate an inductor, as is shown in FIG. 34. However, such aconfiguration may be unduly bulky, difficult to locate in a housing, andprone to breakage.

In order to alleviate such problems, and provide other advantages, inthe stud finder 101 of the present exemplary embodiment, utilizes as aninductor 3011 inductive coils 4100 and 4101 located on a printed circuitboard (PCB) 4000 as is shown in FIGS. 35 and 36. The printed circuitboard 4000 has multiple layers of copper conductor alternating withlayers of substrate. For example, the printed circuit board 4000 mayhave four layers. When the printed circuit board 4000 has four layers,first and second electrodes may be on a first layer. This may comprise,for example, any of the first and second electrode structures shown inany of the embodiments of the present application. For example,electrodes 310 and 304; 602 and 604; 702 and 704; 802 and 804; or 902and 904 may be on the first layer of the printed circuit board 4000.FIGS. 37 and 39 illustrate electrodes 702 and 704, but the otherelectrodes may be used similarly.

FIG. 35 illustrates one layer of the printed circuit board 4000, asecond layer 4002. The first inductive coil 4100 is printed on a secondlayer 4002 of the printed circuit board 4000.

FIG. 36 illustrates the third layer 4003 of the printed circuit board,upon which the second inductive coil 4101 is disposed.

As shown, the first and second inductive coils 4100, 4101 form acircular shape near the outside of the printed circuit board layers4002, 4003.

The shield layer shown in FIGS. 26 and 27 may be on a fourth layer ofthe printed circuit board 4000. Separating the shield layer and theelectrodes 310 and 304; 602 and 604; 702 and 704; 802 and 804; or 902and 904; by layers of the circuit board may be helpful for maintainingthe signal from the electrodes. In other embodiments, the printedcircuit board 4000 may have more or less than four layers. Additionallayers could accommodate additional components, such as a thirdinductive coil. Alternatively or additionally, the additional layer orlayers could provide for having electrodes on different layers.

In this first layer of the printed circuit board is a top layer. Thesecond layer 4002 is next, the third layer 4003 is lower than the secondlayer 4002 and the fourth layer is a bottom layer. That configurationmay be inverted such that the first later is the bottom layer and thefourth layer is the top layer. Accordingly, the circuit board 4000 layerwith the electrodes disposed thereon may be disposed closest or farthestaway from a rear of the housing 1500. In another exemplary embodiment,the inductive coils 4100 and 4101 could be spaced on the farthest apartlayers. For example, coil 4100 may be on a first layer and coil 4101 maybe on the third layer.

FIG. 37A illustrates the printed circuit board 4000 with all four layersand components on all four layers. As is well known the variouscomponents and layers can be connected by electronic tracings or othermeans. There may be vias and holes in the printed circuit board Asdiscussed above, the electrodes 702 and 704 are exemplary, and any ofthe described electrode arrangements could be used in conjunction withthe inductive coils 4100 and 4101. As shown in FIG. 37A, the inductivecoils 4100 and 4101 are located radially outside of the electrodes 702and 704 such that they surround the electrodes 702 and 704. This allowsthe inductive coils 4100 and 4101 to have a significant size. The sizeprovides for a greater signal for detecting a metal object. Anotheradvantage of the exemplary embodiment with the inductive coils 4100 and4101 concentric with the electrodes is that the electrodes 702 and 704both have the same focus of signal. That is, the signal from theelectrodes 702 and 704 is at a maximum at the same time that the signalfrom the inductive coils 4100 and 4101 is at a maximum. In eachinstance, this is at the horizontal center of the stud finder 101.

As additionally shown in FIG. 37A, there is a gap 4200 between theinductive coils 4100, 4101 and the electrodes 702, 704. The gap 4200 isbetween the outer circumference formed by the electrodes 702, 704 andthe inner circumference of the inductive coils, and is formed in aradial direction. The gap 4200 may be 0.025 inches or greater, 0.03inches or greater, 0.05 inches or greater, 0.075 inches or greater, 0.1inch or greater, 0.125 inches or greater or 0.15 inches or greater. Thegap 4200 helps to reduce any unwanted interference between theelectrodes 702, 704 and the inductive coils 4100, 4101. In the exemplaryembodiment, the gap 4200 is substantially uniform.

As shown in FIG. 37A, there is also a gap 4201 between the inductivecoils 4100, 4101 and the shield electrode 705 (the shield electrode waspreviously described with respect to other embodiments). In theexemplary embodiment, the shield electrode 705 is circular and largerthan the combined area of the electrodes 702 and 704. Accordingly, inthe exemplary embodiment the gap 4201 is smaller than the gap 4200. Thegap 4201 is between the outer circumference of the shield electrode 705and the inner circumference of the inductive coils 4100, 4101, and isformed in a radial direction. The gap 4201 may be 0.025 inches orgreater, 0.03 inches or greater, 0.05 inches or greater, 0.075 inches orgreater, 0.1 inch or greater, 0.125 inches or greater or 0.15 inches orgreater. The gap 4201 may also help to reduce any unwanted interferencebetween the electrodes 702, 704 and the inductive coils 4100, 4101. Inthe exemplary embodiment, the gap 4201 is substantially uniform.

In an alternative exemplary embodiment, the inductive coils may beplaced inside the electrodes. That is, rather than the inductive coilssurrounding the electrodes, the electrodes may surround the inductivecoils. In such an exemplary embodiment, the central area between theelectrodes may be made larger in order to accommodate the inductivecoils and the hole 204. The gap may be of the sizes previouslydescribed. If the inductive coils are placed inside the electrodes, theelectrodes surround the inductive coils. As with the previouslydescribed embodiment, the electrodes and the inductive coils bothprovide maximum signal at the same point (the center of the hole). Thenumber of windings of the inductive coils may have to be increased toprovide sufficient signal.

As is additionally shown in FIG. 37A, the electrodes 702 and 704 arespaced apart from one another along a centerline. This allows fortracings and other electronic connections and components.

FIG. 37B illustrates potential cutouts 4500 of the electrodes for traces4600.

FIG. 38 illustrates an electronic hardware block diagram 2500 includinga metal detector 2530 with inductive coils 4100 and 4101. The metaldetector 2530 is operatively connected to the microcontroller 2502, sothat the microcontroller 2502 can process a signal from the metaldetector 2350 and turn on LED 3000 to indicate when a metal object hasbeen detected. As discussed above, the output may be a single LED 3000or more or different indicators. The metal detector 2350 may workaccording to the description of FIG. 33B, where the inductor 3011 isprovided by inductive coils 4100 and 4101.

FIG. 39 illustrates the microcontroller's connections with the inductivecoils 4100, 4101, shield and electrodes 702, 704. The connections worksimilarly to those described with respect to FIGS. 26 and 27, but havethe additional inductive coil components 4100 and 4101.

FIG. 40 illustrates a firmware or software flowchart. The flowchart ofFIG. 40 is the same as that of FIG. 28, and the operations described arethe same and are not repeated again here. The flowchart of FIG. 40 addsmetal detection 2820 performed by the previously described metaldetector 2350 for the stud finder 101 and indicates if metal is detectedat step 2822.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word “comprising” or “including”does not exclude the presence of elements or steps other than thoselisted in a claim. In a device claim enumerating several means, severalof these means may be embodied by one and the same item of hardware. Theword “a” or “an” preceding an element does not exclude the presence of aplurality of such elements. In any device claim enumerating severalmeans, several of these means may be embodied by one and the same itemof hardware. The mere fact that certain elements are recited in mutuallydifferent dependent claims does not indicate that these elements cannotbe used in combination.

Although the description provided above provides detail for the purposeof illustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the disclosure is not limitedto the expressly disclosed embodiments, but, on the contrary, isintended to cover modifications and equivalent arrangements that arewithin the spirit and scope of the appended claims. For example, it isto be understood that the present disclosure contemplates that, to theextent possible, one or more features of any embodiment can be combinedwith one or more features of any other embodiment.

What is claimed is:
 1. A device for locating an object, the devicecomprising: a housing including a first hole; and a sensor carried bythe housing and comprising two or more electrodes that are positionednext to each other to form a substantially circular configuration,wherein the sensor includes a second hole formed in the center of thecircular configuration, and wherein the second hole is axially alignedwith the first hole.
 2. The device of claim 1, further comprising ashield electrode carried by the housing and disposed behind the sensor.3. The device of claim 2, wherein the shield electrode has a circularconfiguration and includes a third hole positioned at a center thereof,and wherein the third hole is axially aligned with the first hole andthe second hole.
 4. The device of claim 1, wherein the substantiallycircular configuration formed by the two or more electrodes comprisesone of a circle and an oval.
 5. The device of claim 1, wherein thesubstantially circular configuration formed by the sensor comprises thetwo or more electrodes having a multi-sided shape that has at leasteight sides.
 6. The device of claim 1, wherein a first diameter of thefirst hole is greater than a second diameter of the second hole.
 7. Thedevice of claim 1, further comprising: one or more processors carried bythe housing, the one or more processors communicatively coupled with thesensor, the one or more processors configured by machine-readableinstructions to: calculate a stud location by measuring a change incapacitance from a fixed capacitance of a wall structure as the studsensor is moved along a surface of the wall structure; and generate oneor more signals to report a result relating to a location of a stud. 8.The device of claim 7, further comprising an audio/visual indicatorconfigured to receive the signal reporting the result relating to thelocation of a stud.
 9. A stud sensor comprising: a housing; a sensorcarried by the housing, the sensor comprising two or moreinterdigitating electrodes; a first shield electrode carried by thehosing and disposed behind the sensor; and a second shield electrodecarried by the housing and disposed around the sensor.
 10. The studsensor of claim 9, wherein the two interdigitating electrodes meet at acurve.
 11. The stud sensor of claim 9, wherein the first shieldelectrode is a circular electrode and the second shield electrode is anannular ring electrode.
 12. The stud sensor of claim 9, wherein the twointerdigitating electrodes form a substantially circular configuration.13. The stud sensor of claim 11, wherein the substantially circularconfiguration comprises one of an oval and a circle.
 14. The stud sensorof claim 9, wherein a hole through the housing and between theelectrodes is substantially centered with respect to the interdigitatingelectrodes.
 15. The stud sensor of claim 9, further comprising: one ormore processors carried by the housing, the one or more processorscommunicatively coupled with the sensor, the one or more processorsconfigured by machine-readable instructions to: calculate a studlocation by measuring a change in capacitance from a fixed capacitanceof a wall structure as the stud sensor is moved along a surface of thewall structure; and generate one or more signals to report a resultrelating to a location of a stud.
 16. The stud sensor of claim 15,wherein the first shield electrode and the second shield electrode iscommunicatively coupled with the one or more processors.